1. Field Of The Invention
The invention relates to a surface-treated abrasive grain with an aluminum oxide base and to an abrasive produced from it, in particular an abrasive applied to a support. 2. Prior Art
Abrasives in the form of an abrasive paper are known which exhibit large empty spaces between the individual abrasive grains and the cutting ups of all abrasive grains are in the same plane, which runs parallel to the plane of a support. To achieve this, a synthetic resin layer or a layer of glue is applied to a support and then a number of abrasive grains are put into a layer of glue by electrostatic means, against gravity, spread out and thus raised (German No. OS 2,125,942).
It has proven to be a drawback that, in such production processes the exposed abrasive grains show a poor jumping and alignment behavior in the electrical field. For example, in German No. OS 2,125,942, it is suggested that the grains be prevented from falling off of the support because of too low a strength of the electrostatic charge by applying a thin film of a highly viscous substance that keeps the grains in place until they are embedded in the layer of glue.
Other drawbacks that occur during electrostatic coating processes are that the voltage in the electrical field must be greatly increased and thus undesirable electrical discharges occur or an increased relative humidity becomes necessary in the processing area.
But all of these measures cannot prevent the coating of the support with abrasive grains from being generally uneven and leading to high rejection rates, since considerable differences in the jumping behavior are detected also within the production charges of an abrasive and thus the production yield is greatly reduced.
A further drawback is that the strength of the integration of the abrasive grains in the support is insufficient, which led to the fact that losses in the abrasive performance of such abrasives had to be accepted.